Properties of calcium ionophore-induced generation of superoxide anion by human neutrophils

Exposure of human neutrophils to the calcium ionophore, A23187, eventuates in a time- and concentration-dependent generation of Superoxide anion (O ₂ ^– ) in the presence but not absence of extracellular calcium. The selective requirement for calcium is demonstrated by the observation that magnesium caused a dose-related inhibition of A23187-stimulated O ₂ ^– generation. Preincubation of neutrophils with cytochalasin B prior to their interaction with A23187 results in a significant enhancement of O ₂ ^– production. The activity of the O ₂ ^– -generating system was maximum at 37°C and was significantly curtailed at lower and higher temperatures. A23187-induced O ₂ ^– generation was inhibited by the sulfhydryl reagents.N-ethyl maleimide (NEM) and iodoacetic acid (IA), and by the metabolic inhibitor 2-deoxy-D-glucose (2-DG) in the absence of glucose and cytochalasin B. Cyanide was inactive. Therefore, A23187 represents a useful pharmacologic probe for investigating the divalent cation and metabolic requirements of the neutrophil O ₂ ^– -generating system.